This invention relates in general to cast vehicle wheels and in particular to a cast vehicle wheel having a hollow core insert and a method for making same.
Light weight vehicle wheels formed from alloys of aluminum, magnesium and titanium are becoming increasingly popular. It is known in the art to cast a one piece vehicle wheel in a multi-piece wheel mold. Referring now to the drawings, there is shown in FIG. 1 a fragmentary sectional view of a typical prior art one piece wheel 10. The wheel 10 has a circular wheel disc 11 which extends across the outboard end of an annular wheel rim 12.
The wheel disc 11 includes a wheel hub 15 having a central pilot hole 16 and a plurality of wheel lug holes 17 (one shown) formed therethrough. The hub 15 is supported by a plurality of wheel spokes 18 (one shown) within an annular sidewall 20 which forms the outboard end of the wheel rim 12.
The wheel rim 12 includes an outboard tire bead retaining flange 21 which extends in a radial outward direction from the sidewall 20. The rim 12 further includes an outboard tire bead seat 22 which is formed in the sidewall 20 adjacent to the retaining flange 21. The rim 12 also includes an outboard tire bead hump 23 formed in the sidewall 20 between the tire bead seat 22 and a deep well 24. A leg portion 25 extends axially across the rim 12 from the deep well 24 to an inboard tire bead hump 26. An inboard tire bead seat 27 is formed adjacent to the bead hump 26. The inboard end of the wheel rim 12 terminates in a conventional inboard tire bead retaining flange 28.
It also is known in the art to fabricate a two piece vehicle wheel by attaching a full face wheel disc to the outboard end of a separately formed partial wheel rim. Typically, the wheel disc is cast while the rim is rolled from strip stock. Such two piece wheels are less expensive to manufacture than a cast one piece wheel while permitting use of stylistic designs for the wheel disc. Both the wheel disc and rim can be formed from alloys of the same light weight metal, or, as a further cost reduction, a wheel disc formed from an alloy of a light weight metal can be attached to a rim rolled from steel. When different metals are used to form the wheel disc and wheel rim, the wheel is usually called a bimetal wheel.
This invention relates to an improved cast vehicle wheel having a hollow core insert and a method for making same.
Due to the geometry of cast wheels, the wheel sidewall, the portion of the wheel where the wheel disc joins the wheel rim, tends to have a thick cross section. Accordingly, a large mass of metal is contained in the sidewall which adds to the wheel weight while not being needed for wheel strength. Therefore, it would be desirable to reduce the weight of the wheel sidewall.
The present invention contemplates a vehicle wheel including an annular wheel rim adapted to support a pneumatic tire and a circular wheel disc formed across an end of the rim, the wheel disc cooperating with the wheel rim to define an annular sidewall. The wheel also includes a hollow core disposed within the sidewall. The hollow core can be either a continuous core which extends circumferentially within the sidewall or a plurality of segments spaced equally about the circumference of the sidewall. The invention also contemplates a continuous or segmented hollow core disposed within the sidewall of a fall face wheel disc.
The invention further contemplates a mold for casting a wheel component which includes a base member and a top core, the top core cooperating with the base member to define a wheel sidewall cavity. The mold also includes a hollow core disposed within the sidewall cavity. A supporting structure positions the hollow core within the sidewall cavity. The wheel component cast in the mold can be a one piece vehicle wheel or a full face wheel disc.
The invention also contemplates a method for casting a vehicle wheel component which includes providing a mold for the component, the mold defining a sidewall cavity. A hollow core is placed within the sidewall cavity. The mold is charged with molten metal and molten metal is allowed to cool and solidify. Finally, the mold is opened and the wheel component and core are removed.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.